Three dimensional structure of the rabbit middle ear muscles was studied using SEM. Three different preparation techniques were used in order to find out the best way for a close observation of the intracellular structures.
1. Osmium-DMSO-Osmium method: In this method, mitochondrial matrices were removed, thus enabling observation of the mitochondrial cristae. The shape of the mitochondria was oval, or short rod. Its number was far smaller than that of the mitochondria found in the intrinsic laryngeal muscles.
2. HCl digestion method: Surface structure of the muscle, such as a motor endplate, could be observed in detail.
3. HCl digestion method combined with mechanical tearing: The muscle tissue was torn longitudinally with a pair of forceps either during or after fixation. Then, specimens were processed for a conventional HCl digestion method. This method enabled observation of both surface and intracellular structure, since the sarcolemma was frequently stripped from the muscle cell.

抄録全体を表示

Histopathology of the lenticular process of incus, which had shown no obvious otologic symptoms, was studied.
From our human temporal bone collection, 20 bones were selected for the present study. They were vertically sectioned and had no clinical history of ear disease.
Most specimens showed bone absorption and fibrosis of the lenticular process to a variable degree. In these specimens, the mucoperiosts of the middle ear were slightly hypertrophied. Such changes were sometimes also observed in the long process of incus. In bone spaces of the ossicle, round-cell infiltration was not seen, which is the quite different from those of the infected ossicle.
From these observations, we conclude that the lenticular process of incus degenerates easily due to mild intermittent infections which might show no otologic symptoms.

抄録全体を表示

Previous time we observed the ultrastructure of the stapedio-vestibular joint of the human fetus and adult with an optical and transmission electron microscopie. This time we still observed it with an transmission and a scanning electron microscopie. As a result we obtained the following results concerning the connective tissue which compose the stapedio-vestibular joint.
1) In the fetus at 11 week stage, immature collagenous fibers and elastic fibers slightly confirmed.
2) Observation with a scanning electron microscopie, fibers in the stapediovestibular joint of the fetus were more thin than the adult's. Thickness of the fibers were irregular and they composed meshy structure.
3) Febers in the stapedio-vestibular joint of the adult were more thick and ran densely.

抄録全体を表示

Many histopathological studies of the iliac bone have been performed, however, that of auditory ossicles is rare. Histopathological changes of the ossicles in renal insufficiency are reported.
The results of historadiographical and histopathological studies of noncalcified ossicles are discussed. Sections stained by the method of Cole showed osteoid seam, calcification front, woven bone, partially calcified osteon and calcified area. Calcification front, woven bone and calcified area appear radioopacity, whereas surrounding structure of vascular channel on the ossicles in the patients with chronic otitis media and renal insufficiency appear radiolucency in historadiograph.
Histradiographical and histological studies on the same sections are suitable for observation of pathological decalcification of the bone.

抄録全体を表示

Otitis media was induced in guinea pigs by intrabullar injection of 1% Carrageenins. The animals were sacrificed for histological examinations at 1 to 14 days respectively. The gross appearance of bulla was most hyperemic and thickened mucosa reaction on 3 or 4 days. Effusion was most abundant on 3 or 4 days. Each specimens are examined under light and electron microscopes. At 24 hours, the subepithelial layer was edematous, and epithelial cells contained electron dense granules. On 3 days, epithelial and subepithelial layer were most remarkably edematous, and macrophages, neutrophils and mast cells were seen in the mucosa. The macrophages contained many electron dense granules and dispersed lysosomes. Some of them were present adjacent to the capillaries, which permeability appeared to be enhanced. The mast cells granules showed less electron density and some of them fused with each other. On 7 or 14 days, the edema had disappeared and infiltration cells were not numerous.

抄録全体を表示

The purpose of this work is to examine the etiologic factors in otitis media with effusions, especially focusing main concern on its chronicity of inflammations in the tympanic cavity. By using modifiecdh Boyden Chamber methed and Agarose method, we investigated the function of neutrophils in MEE, the effect of MEE on chemotaxis and chemotactic factors in MEE. The results were as follows;
1 The chemotaxis of neutrophils in MEE was decreased compared with that of peripheral blood reutrophils. 2 About 20% of MEE, exemined by Agaroce plate method, sowed chemotactic activities. 3 Peripheral neutrophils co-incubated wit MEE showed decreased chemotaxis in about 67% of cases and increased one was in about 20% of cases.

抄録全体を表示

We investigated soluble immune complex levels in middle ear effusions (MEE) of 36 cases (53 ears). By Clq solid-phase ELISA method, soluble immune complex levels in sera and MEE of cases with otitis media with effusion. The results were as follows:
1) Immune complex levels in MEE were significantly higher than that in sera,
2) Immune complex levels in MEE tended to become higher as the lesions in the tympanic cavity were prolonged,
3) Cases with chronic OME of purulent type and mucopurulent type showed relatively higher immune complex levels than acute-purulent cases.
These results may strongly suggest that soluble immune complexes in MEE play a important role in the pathogenesis of OME, and we prefer to classify otitis media with effusion into a kind of immune complex disease.

抄録全体を表示

Little was known about the biochemical properties of human middle ear effusions. Recently it was reported that mucus of upper respiratory tract might affect the mucocilliary function.
Therefore, we analysed the carbohydrate content of glycoprotein fractions in the human middle ear effusions by GLC (gas liquid chromatography). All middle ear effusions contained appreciable amount of neutral sugar, hexosamine and sialic acid. Component of neutral sugar were fucose, mannose, galactose and glucose.
All sugar components to protein in mucoid effusions were enriched from serous effusions, especially fucose and N-acetylneuraminic acid were enriched about 3-fold. On the other hand, the relative distribution of sugar of glycoprotein fractions showed similar tendency except fucose and N-acetylneuraminic acid. We suspected these sugars resulted from acid glycoprotein according to Palva's data.

抄録全体を表示

Acoustic compliance of the tympanic membrane measured in tympanometry depends mainly on both the volume of the middle ear cavity and the elasticity of the tympanic membrane. We try to measure these values simultanuously in the ear with normal tubal function and with no eardrum perforation by observing the air pressure of the external auditory canal and tympanogram before and after the deglutition which causes inflation of the tympanic membrane. Measured equivalent volume of the eardrum compliance was smaller than that of the middle ear cavity in normal ears which means that the former gives greater contribution in determining the eardrum mobility than the latter. The resultant acoustic compliance calculated from these values was somewhat greater than that obtained from tympanometry.

抄録全体を表示

Using a fine flexible endoscope with a diameter of 2.7mm, opening processes of the Eustachian tube were examined in normal adults, patients with cleft palate or abnormally patent tube. During swallowing and phonation of vowel “a”, inside of the tube was observed up to the isthmus. It was revealed that 1) the pharyngeal end of the tube opens both by lateral pull of the anterior tubal wall and medial displacement of the torus tubarius, 2) inside of the tube opens for a very short period during swallowing by lateral pull of the tensor veli palatini muscle, but it does not open during phonation, 3) paradoxical movement of the tube observed in cleft palate cases were considered to be due to abnormal courses of the tubal muscles, 4) abnormally patent tube showed consistent opening up to the isthmic part even at rest. Thus dynamic processes of tubal opening were clearly demonstrated by endoscopy.

抄録全体を表示

To determine the detailed mechanism of fluid clearance from a closed tympanum, microscopic observation of fluid clearance from a closed feline tympanum, and a measurement of pressure change in a feline and a human middle ear were conducted.
It was revealed that fluid in a closed tympanum was cleared out by tubal opening and closure. With each clearance, negative pressure increased in a closed tympanum due to inadequate ventilation. This negative pressure was considered to gradually prohibit tubal opening and consequently stop fluid clearance. We concluded that ventilation of the closed tympanum is indispensable for clearance function of the Eustachian tube. It was also suggested that fluid in a human middle ear might be expelled in the same manner.

抄録全体を表示

Electron irradiation was done to the pharyngeal orifice of the eustachian tube in guinea pig to observe the pathological change of middle ear structures followed by tubal dysfunction. 2000 rads alone, 2000 rads × 2 (with one month interval), 3000 rads, 3000 rads × 2 (with one month interval) and 3000 rads + 1000 rads × X (with 2 weeks' intervals) were irradiated respectively and pathological changes of the middle ear structures using H-E staining were observed 1 week, 2 weeks, one month, 2 months after the cessation of irradiation. The results obtained were as follows. Early changes, i. e., one or two weeks postirradiation consist of thickening of submucosal connective tissue layer and infiltration of inflammatory round cells. At the mid-stage post irradiation, i. e., one month later, cuboidal and columnar changes in epithelial layer appeared. At the same time connective tissue layer was more thickened with numerous fibroblasts. Occasionally osteoclast and osteoblast were found beneath the periosteum. At the final stage in our series, i. e., two months postirradiation, new bone formation and remodelling became obvious with occasional fat degeneration.

抄録全体を表示

It has been commonly recognized that the development of mastoid air cell system is inhibited in chronic middle ear infections. However, it has not been proved whether underdeveloped air cell system causes chronic middle ear infections or it is a result of inflammation in the middle ear cleft.
Tympanic bulla of the pig is composed of thin cortex and well pnematized air cell system. Therefore, the authers studied the effect of inflammation in the middle ear cleft on the air cell system using these pigs.
Air cell system of tympanic bulla was developed by the apposition and the resorption of bone in the cortex. Inflammation extending to the cortex inhibited only the absorbing activity and not affected the appositive activity. The impaired activity produced diminution of the space resulting from the resorption of bone. This space became later air cell, so that the tympanic bulla suffering from middle ear infections was sclerotic with increase of the thickness of the bone by apposition.

抄録全体を表示

Cause of the developmental inhibition of pneumatization of mastoid cell is not yet elucidated, even though, there are several hypotheses in debate.
We have reported previously that chronic inflammation in the middle ear inhibited the pneumatization of mastoid cells in pigs and also the poor pneumatization might be caused by the disturbance of bone metabolism.
We have made further study on the effect of the chronic inflammation to the pneumatization of mastoid cells increasing the numbers of cases and using 43 healthy matured pigs (180th days after birth).
As the result, 13 cases out of 43 showed the developmental inhibition of pneumatization (severe inhibitions in 12 cases and moderate one in 1 case).
Concerning the findings of pre-punctured tympanic membrane, the punctured hole remained open in 8 cases and found closed in 5 cases.
The 4 cases with closed tympanic membrane tended to show severe inhibition of pneumatization and inflammatory state histologically comparing with those with the perforated tympanic membrane.
Consequently, the perforation of tympanic membrane seemed to play a significant role inducing ventilation effect in the chronic inflammation of middle ear.

抄録全体を表示

The purpose of this study was to investigate histopathology of the epitympanum in different types of otitis media. In every type of otitis media, evedent histopathological changes were observed in the epitympanum. In serous or mucoid otitis media (5 cases), common findings in the epitympanum were thickening of the mucosa and the submucosa, and effusion dominantly distributed by neutrophils. In centrally perforated otitis media (3 cases), the thickening of the mucosa were common. In cholesteatomatous otitis media (3 cases), squamous epithelium has invaded in the epitympanum and resorption of the ossicles were seen.

抄録全体を表示

The distribution pattern of ciliated cells in the normal mucosa of the guinea pig middle ear was determined by means of scanning electron microscope. In general, the density of ciliated cells decreased from the tympanic tubal orifice of the eustachian tube to the tympanic bulla and to the surface of the cochlea. On the tympanic bulla of the ipsilateral side against the tympanic tubal orifice, there was a peninsula with ciliated cells radiated from the bony ridge connecting on the cochlea. Most ciliated cells possessed about 80-140 cilia. The surface shape and size of non-ciliated cells were variable. Ciliated epithelial cells in the floor adjacent to the tube may play an important role in an active mucociliary mechanism as in other parts of the upper respiratory system.

抄録全体を表示

Mucosal biopsies and mucous effusion from the middle ear of seven children, aged 4-6, with secretory otitis media, were studied by electron microscopy. The biopsied promontrial epithelium showed that the ciliated cells had decreased in number and most part of them were lined by cuboidal cells containing abundant light granules with or without a central dark core. It was also found that there were numerous infiltrative cells such as neuitrophil leucocytes, lymphocytes and macrophages in the mucous effusion had degenerated and their debris including free nuclei, mitochondria, lysosomes etc., were remaining in the fluid. These findings in the present study seem to suggest that dysfunction (or hypofunction) of the clearance of the middle ear is a causative factor of the otitis media with mucouse dffusion.

抄録全体を表示

Three groups concisting of 40 guinea pigs were exposed to 4kHz pure tone at 115-120 dB SPL for 30 min. (Group A), 2hrs. (Group B) and 6hrs. (Group C). ABR was recorded on each animal, before and after exposure. Elevated thresholds recovered almost to the pre-exposure level within 3 to 7 days. SEM findings after exposure showed bending of auditory hairs in outer hair cells between upper basal turn and lower second turn and also, the first row of these region was damaged severely. These alterations showed poor tendency to recover even one week after exposure in Group B and C. In SDH stainings of the surface specimens of Corti's organ, the first row of outer hair cells in the lower second turn showed swelling and decrease in SDH activity. These changes were observed only in Group C if one week after exposure. These results suggest that alterations of auditiry hairs and the swelling of hair cell body observed in one week after exposure are sines of irreversible changes.

抄録全体を表示

The effect of acute hypertension, induced in rats by intravenous injection of methoxamine chloride (Mexan), on the stria vascularis and spiral ligament was studied electron microscopically with the tracer method of horseradish peroxidase (HRP). A large amount of extravasation of HRP occurred in the stria vascularis, which was due to increased vesicular transport. The leaked HRP spread into intercellular spaces, but was prevented spreading towards the endolymph by zonulae occludentes between marginal cells and towards the perilymph by zonulae occludentes between basal cells. The reaction product was occasionally found between basal cells. No leakage of HRP from capillaries was observed in the spiral ligament although some labelled micropinocytotic vesicles were present in the endothelium. It is suggested that, under acute hypertensive condition, areas of zonulae occludentes bordering the stria vascularis play an important role in a barrier to HRP.

抄録全体を表示

Ferritin transport through the strial capillary during kanamycin intoxication was examined under a transmission electron microscope. Twelve guinea pigs were treated intramuscularly with kanamycin (400mg/kg/day) for 2-3 weeks. When a full hearing loss was recognized by estimating Preyer reflex or ABR, ferritin was given intravenously, and animals were sacrificed 1/3, 1 and 2 h later. At 1/3 h, ferritin was present not only in the endothelial cell but also in the basal lamina diffusely and within vesicles in the strial cell. On the other hand, it was discharged into the endolymphatic space. At 2 h, ferritin was seen on the luminal surface and in the cytoplasm of the endolymphatic cells of Reissner's membrane. These results suggest that the basal lamina of the strial capillary was altered qualitatively by kanamycin administration.

抄録全体を表示

It is known that most forms of hypertension are associated with total peripheral resistance (TPR), but it has not yet been defined how each organ contributes to the elevated TPR. In this study, we investigated the effect of blood pressure on the blood flow in the inner ear as compared with other organs using normotensive rats (NR), spontaneously hypertensive rats (SHR), and renal vascular hypertensive rats (RHR). The cardiac output and the regional blood flow were measured by a radioactive microsphere technique in a conscious state. The hemodynamics of the inner ear and other organs and the effects of a converting enzyme inhibitor (SA-446) on the regional blood flow were compared between NR, SHR, and RHR. The blood pressure measurements in NR, SHR, and RHR were 107, 152 and 185 mmHg, respectively. The organ blood flow was reduced in all examined organs, including the inner ear, except for heart, in SHR and RHR compared with NR. The reduction was greater in RHR than in SHR. The blood pressure fell following the i. v. injection of SA-446. The effect of this inhibitor was strongest in RHR followed by SHR and NR in decreasing order of the effect.

抄録全体を表示

In order to clacify the cell kinetics of the component cells of the cochlea, we have carried out the Feulgen-DNA cytofluorometry on these cells of human by “serial section method” developed by ourselves.
The cochlea was embedded in glycol methacrylate, water-miscible resin (Acrytron E) at 4°C and serial sections of 3 micron thickness was obtained. The sections were stained with azocarmin G and acriflavine-Feulgen and examined by fluoromicroscope. By this staining and by changing excitatory light wave length it was possible to identify the cells and to measure the DNA content of its nucleous on the same section.
The results obtained from 3 autopsy cases revealed almost all the component cells of the organ of Corti gave diploid G1 pattern in DNA distribution. Interestingly, however, some of Hensen's cells have tetraploid pattern.

抄録全体を表示

Ten rabbits received injection of Indian ink into the stylomastoid foramen. Observation of the serial sections of their temporal bones revealed Indian ink infiltration into the subarachnoid space along the facial nerve, the auricular branch of the vagus nerve, and the tympanic nerve. Along the cochlear nerve, superior vestibular nerve and inferior vestibular nerve, the infiltration was found as far as the fundus of the internal auditory meatus, but not to the spiral ganglion, the crista ampullaris, the macula sacculi or the macula utriculi. In some cases, Indian ink reached the subarachnoid space, and infiltrated into the scala tympani, the scala vestibuli and around the saccule by way of the cochlear aqueduct, but did not inside the membranous labyrinth.

抄録全体を表示

The ototoxicity of various aminoglycoside antibiotics, tobramycin (TOB), gentamicin (GM), kanamycin (KM), amikacin (AMK), and dibekacin (DKB), was evaluated by a single injection into the facial nerve through the stylomastoid foramen. Twenty-five albino rabbits weighing about 3 kg were used. Each drug was disolved 100mg/ml and 0.04ml given. Hair cell damage was observed 10 days after the injection. Hair cell damage in the rabbits injected with TOB or GM was severer than in those injected with KM, AMK or DKB. The result coincides with that of general administration of these drugs. Therefore, it is concluded that this method is useful in the evaluation of ototoxicity of aminoglycoside antibiotics.

抄録全体を表示

Changes in vertebral and common carotid arterial blood flow caused by intraveous administration of adenosine triphosphate (ATP), betahistine, papaverine, diphenidol were examined in anesthetized dogs. The increase of blood flow caused by ATP was appeared dose-dependently from dose of 1 μg/kg. The potency of this effects were followed: Betahistine>ATP, papaverine>diphenidol. Then, the effects of intraduodenally administered ATP on the vascular system of the inner ear were examined in guinea pigs. The increase in the diameter of the blood vessels was observed in cochlear and vestibular system. The effects began to appear at dose of 100 mg/kg and became maximum at dose of 500mg/kg. The effects were most prominent 15 minutes after administration and became decreased gradually to normal value 90 minutes later.

抄録全体を表示

The effect of making granulation and resulting fibrotic changes in the internal auditory canal (IAC) following powdering of metyl methacrylate was examined in 24 special pyrogen free cats. Six months prior to the measurements the IAC was opened by the middle fossa approach and the superior wall of the meatus was removed. Metyl methacrylate powder was inserted into the meatus. The perilymphatic oxygen tension by the polarographic technique, hydrostatic pressure by servo-controlled micropipet system, CM, AP, were recorded. The initial perilymphatic PO₂ values of the sides of reduced vascular supply and the contralateral control ears werre 11.8±3.8 mmHg and 23.3±6.7 mmHg, respectively. Sensorineural hearing loss (high tone loss of on average 20 dB) was noted on the ears of reduced vascular supply. No considerable difference was present in the measured perilymphatic pressure with patent cochlear aqueduct, while statistical difference was noted in the dynamic perilymphatic pressure changes in the ears of reduced vascular supply with obliterated cochlear aqueduct.

抄録全体を表示

Among the existing methods to estimate the level of oxygenation in the inner ear, only the polarographic technique and the microsphere method are accepted to be reliable. Using the former technique the effect of nicardipine hydrochloride (YC-93) on the perilymphatic oxygenation was examined on 8 cats. In order to estimate the effect of the drug without the changing influence of the systemic blood pressure (SBP), an on-line digital analysing system was developed where the physiological parameters as oxygen tension, cerebrospinal fluid pressure (CSFP), central venous pressure (CVP), SBP, and body temperature are 12 bit digitally converted and analysed. The precise features of the system are presented with the following results; 1) The perilymphatic oxygen tension did not follow the decrease in SBP when 10 micrograms/kg of YC-93 was intravenously administrated. 2) The analysis of the correlation coefficient between SBP and CSFP of consecutive 100 seconds in 5 seconds interval indicated a marked influence of the drug (when administrated 30microns/kg/hour) to the autoregulative properties of the inner ear vessels.

抄録全体を表示

The influence of furosemide on the cochlea, liver and kidney of guinea pig was studied in vitro by measurement of ¹⁴CO₂ oxidized from [1-¹⁴C] glucose with scincilation counter. Although the inhibitory effects of furosemide were seen in each organ, this was most dominantly observed on the cochlea. In order to confirm the sites of the inhibition on this metabolic process, the activity of glyceraldehyde-3-phosphate dehydrogenase (G3PDH) was estimated by the histochemically after Himmelhoch. This enzyme activity in each organ was equally inhibited by the administration of furosemide, this was, however, recovered most rapidly in the liver tissue by the lapse of time. In conclusion it is most likely that inhibition of glucose oxidation, especially at the step of G3PDH, is involved in the mechanism of Oto- and nephrotoxicities of loop diuretics.

抄録全体を表示

The distribution of ¹⁴C-labelled lidocaine in the guinea pigs after intravenous injection was studied. The mesurements of the radioactivity of several organs were made using a liquid scintillation counter (Packerd Tricarb, Model 460C). General distribution was studied by whole-body autoradiography. The values at 5 and 30 minutes after administration in cerebrum, brain stem, cerebellum were considerable. On the other hand, that of cochlea was a little. A autoradiography, which was made 30 minutes after administration, revealed the distribution of the drug in cerebrum, brain stem, cerebellum, cochlea. 4 hours later, the distribution in cochlea was almost negligible. The distribution in other organs were also negligible 8 hours later. Based on this findings, we speculate that the acting site of lidocaine on tinnitus may be central.

抄録全体を表示

These experiments are concerned with the frequency distribution of two-tone suppression in forward masking. In each experiment, the threshold of a 15ms probe tone following a 600ms narrow-band masker (band-width 200Hz) was determined as a function of probe frequency.
In experiment I and II, this was done for two maskers which had previously been fixed for their spectrum level difference 20dB and central frequency f_s of suppressing masker was parameterically varied. The maskers were equally effective only in a restricted frequency region around f_m, a result which is not consistent with idea that suppression to a simple reduction in level of the suppressed masker.
Also, experiments were provided for the difference between suppression by a higher-f_s and lower-f_s. These effects can be explained with the help of the Hall's model. Consequently, two-tone suppression requires both the non-linearity and a second filter.

抄録全体を表示

Responses of the on-type neuron of the inferior colliculus in rabbit to tonal stimuli were examined. 8 sets of stimulus tone were used, each of them was consisting of f_I and f₂ tone burst and complex tone that onset of the f₂ tone begins 50msec later than onset of the f_I tone and frequency ratio of f_I to f₂ were as follows: I/5, 2/7, I/3, 2/5, I/2 and 2/3. Neural responses to f₂ tone and f₂ element in complex tone were studied. From this investigation, responses of many neurons to f₂ tone were diminished under f_I tone but a few neurons showed more firing to f₂ tone under same condition than f₂ tone alone. This data suggests that response of on-type neuron was decided by spacial and intensity condition of stimulus tone and it has many neural inputs, activity of which all were controlled by elements of stimulus tone. Between CF and Q_IO dB of each neuron, f_I, f₂ and neural response no difinite relationship could be found out in this study.

抄録全体を表示

ABR were recorded from the vertex of adult cats concurrently with the recording of single unit activity in the ipsilateral inferior colliculus. The latencies of ABR peak 5 (P5) ranged from 4.5 to 7msec., while some units had constant latencies within the range of P5 latencies. However, these units were few in the inferior colliculus. The correlation between the latency of P5 and that of unit response in the inferior colliculus was analysed by changing the intensity of stimuli. There was not statistically significant correlation between the latencies of P5 and those of units which had constant latency from 4.5 to 7msec. The result suggests that the ipsilateral inferior colliculus has only a small part in ABR P5.

抄録全体を表示

Brain stem evoked responses (BSER) by electrical stimulation of the cochlea were studied both with normal and KM deafened guinea pigs. The sites of stimulation were 1) the promontory - round window, 2) the scala tympani of the basal turn with bipolar electrode, 3) the scala tympani of the basal turn - scala vestibuli of the third turn, and 4) the modiolar acoustic nerve. The electric stimulus was a 10 kHz one-cycle sinusoid. There were no significant differences in the threshold between normal and deafened animals. Though BSER thresholds varied considerably, mean thresholds proved lower in the order of 2) → 1) → 3) → 4). When the threshold of myogenic response is regarded as a upper limit of the electric hearing, the dynamic range, that is the range between the thresholds of BSER and those of EMG, proved wider in the order of 1) → 2) → 3) → 4).

抄録全体を表示

To know the origin of AP we compared Input-Output Curves (I. O. C.) of the field potentials in the Rosenthal canal (AP (R)) with that of AP at the bony wall of the cochlea (AP (W)). AP (R) recorded with micropipettes shows two negative waves (N1, N2) as same as AP (W). As correlations of I. O. C. of latency and amplitude of AP (R) N1 and AP (W) N1, AP (W) N2 are so high (All of them are above 0.9), we conclude that both AP (W) N1 and AP (W) N2 are the action potentials of the cochlear nerve. The differences of their latencies are as follows: latency of AP (W) N1 is about 0.2 msec shorter than that of AP (R) N1 (p<0.005). Latency of AP (W) N2 is about 0.4 msec shorter than that of AP (R) N2 (p<0.005). The difference of latency between N1 and N2 of AP (W) is about 0.2 msec shorter than that of AP (R) (p<0.005) and the correlation of them is low (correlation coefficient is 0.16). As the cochlea is isoelectrical, these results show that AP (W) N1 is the action potential of the cochlear nerve near the habenula perforata of the basal turn where the spikes are initially produced and AP (W) N2 does not originate from the action potential of the cochlear nerve in the Rosenthal canal or near the habenula perforata of the basal turn.

抄録全体を表示

Hypothermia was induced by surface cooling in 13 anesthetized guinea pigs and the effects upon the CM, SP and N₁ recorded in the round window were examined. Recording was performed at 1 to 1.5 °C steps of cooling and the temperature was measured in the intracranial space. The amplitude of the CM was almost linearly decreased as a function of the temperature decline. The SP was, however, exhibited variable changes and no consistent result was obtained in each animal. The N₁ showed no change or slight increase in amplitude upto about 28 °C and a linear decrease thereafter. The N₁ latency was almost linearly increased at the rate 0.1 ms/°C. The effect of interstimulus interval shortening (adaptation) upon the N₁ amplitude became less remarkable as the temperature was lowered. These results are relevant to the animal experiments reported by others and our human EcochG studies.

抄録全体を表示

It is known that the positive part of the saccular endolymphatic potential is not produced in the saccule but transmitted from the cochlea and attenuated to about 10% of the original value. In case of Meniere's disease, the saccule as well as the cochlea exhibits the endolymphatic hydrops. The present experiment aimed to study the effect of the hydrops to the both potentials. The endolymphatic potentials in the cochlea (CEP) and the saccule (SEP) were recorded and the response to anoxia was examined in 9 guinea pigs with the endolymphatic hydrops 1 month postoperatively. The magnitudes of CEP and SEP in the hydrops ears were 57.64±9.3mV and -0.1±4.1mV, respectively. These values were significantly lower than those of the normal ones (CEP 81.9±4.1mV, SEP 3.0±4.5mV). Anoxia was made by stopping the respirator. Both potentials in hydrops ears were less sensitive to anoxia. Namely, the time elapsed from the onset of anoxia to the decline of the potential was prolonged and the decline rate was also shown them the normal. The results suggest that the strial metabolism and possibly the membrane permeability are inhibited in the hydrops ear.

抄録全体を表示

The EP is remarkably increased when the scala tympani is perfused with the solution of 150mM KCl. The purpose of this experience is to know the mechanism underlying this phenomenon. The concentration of the potassium ion in the endolymphatic spase increased by 3.0±0.3mM (n=4) when the EP increased to the maximum value approximately two miniutes after the start of the perfusion. The electrical resistance of the endolymphatic wall was 3.68±0.28 KΩ (n=4) on the pre-perfusion, and increased 3.98±0.28 KΩ (n=4) on the peak time of the EP. The CM decreased to less than 50% of its original level at the same time. A hundred mg/kg of furosemide was administrated intravanously a few minutes after the start of the perfusion, which produced relatively smaller magnitude of the negative EP compared to that normally appearing during anoxia. The conclusion is that the cause of the remarkable increasing in the EP during the perfusion is considered not to be the disappearance of the potassium ion diffusion potential, but probably to be the stimulation on the generator of the positive component of the EP and/or the increasing in the electrical resistance of the endolymphatic wall.

抄録全体を表示

Perilymphatic perfusion allows us the direct approach of drugs to the cochlea. Using this method the effect and localization of ouabain (a potent Na⁺-K⁺ pump inhibitor) was examined by electrophysiologic, electronmicroscopic and radioautographic technique. Sixteen minutes of ouabain perfusion at the concentration of 10^-3 and 10^-5 M depressed endolymphatic DC potential (EP) dose-dependently and coused the ultrastructural changes mainly in the marginal cell. Besides this area the ouabain was localized extracellular space of the spiral prominence, probablly indicating the route of disappearance of the drug from the cochlea. These findings together with other's data strongly suggested that Na⁺-K⁺ pump existed in the marginal cell of the vascular stria and has important role for the generation of EP.

抄録全体を表示

Intravenons injection of furosemide (FUR) induces a fall of endocochlear potential in guinea pigs. Falling patterns were analyzed with the following equation. With an aid of a micro-computer (Fujitsu Micro 8), a least squares method was applied in the analysis. Doses of furosemide were 20, 30, 40 and 50 mg/kg.
_??_
where Y: aquired EP L: free furosemide M: initial EP r: reaction rate (decrease rate of EP)
The model values fitted well to the obtained values. The results from the model are as follows.
1. Reaction rate r stayed constant independent of the EP fall.
2. The amount of furosemide in blood corresponds linearly to the decrease of EP.
This indicates that furosemide blocks the EP generation pump directly.

抄録全体を表示

To observe the effect of acute hypertension on EP decreasing action of furosemide, the present experiment was performed on guinea pigs using angiotensinamide. In one group, 30 or 40 mg/kg of furosemide was injected, while in the other, angiotensinamide was continuously injected through a microinjector prior to the furosemide (30 or 40 mg/kg) injection. In angiotensinamide-furosemide group, blood pressure increased after the angiotensinamide injection and then decreased after the furosemide injection. In this group, the decrease of EP was greater than in the furosemide group. Therefore, it became evident that angiotensinamide potentiates the EP decreasing action of furosemide. Regarding the effect of angiotensinamide, it could be conceived that acute hypertension facilitated the access of furosemide to the action site in the stria vascularis.

抄録全体を表示

Endocochlear potentials are examined simultaneously at the two different places in the guinea pig cochlea and vestibuli. About 80mV is recorded at the basal turn of the cochlea and about 3mV is recorded at the semicircular canal. They were designated CEP for cochlear EP and VEP for vestibular EP. (1) Furosemide injection reduced the CEP to negative value rapidly, but it kept the VEP unchanged. (2) Asphyxic anoxia for 150 seconds reduced both potentials to negative value in normal animals. (3) The VEP felt down under negative value and the CEP stayed positive value after asphyxic anoxia in KM intoxicated animals. (4) The completely reverse phenomenon occure in SM intoxicated animals.
It was concluded that the VEP and the CEP are independent each other and potentials in the hair cells contribute to a construction of EP from point of view that KM and SM damage the hair cells in the cochlea and vestibuli respectively.

抄録全体を表示

A theoretical analysis of EP generating system was made to constitute a model which can consistently explain the EP decrease curve on furosemide administration. For this purpose we modified the endocochlear curcuit model with the idea of “channels” and introduced all or none blockage hypothesis of furosemide on potassium pumps. A satisfactory approximation could be obtained from the simulation of this model.

抄録全体を表示

Marginal structure of the tectorial membrane in the neonatal hamster was observed by SEM with the styrene resin cracking method. Golden hamsters were decapitated under ether anesthesia everyday from the day of birth until 20 days after birth. Inner ears were extirpated within 10 minutes in chilled 1% paraformaldehyde-3% glutaraldehyde solution and refixed in 2% osmic acid. From 2-3 days after birth, marginal complex forms a network and oblique strands to the basal direction make an attachment to the surface of Hensen's cells. This attachment gradually disappear from about a week after birth when marginal pillars appear on the surface of the third row of Deiters' cells and is not observed after 10 days after birth at all.

抄録全体を表示

This study aimed to investigate the inner ear changes due to the aging of mice. The authors kept healthy mice for their life time under normal conditions. Mice were sacrificed at 15, 18, 24 months respectively. Changes of the inner ear were studied under light and scanning electron microscope. The following results were obtained;
1) Almost all of the outer hair cells were gone completely, but only a few inner hair cells were preserved under light and electron microscope.
2) Cells of the spiral ganglion and fibers of the modiolus were found to be decreased pronouncedly.
3) Atrophy of the stria vascularis was seen in the basal turn of the cochlea at the age of 18, 24 months.
4) Degenerative change of the organ of Corti and the spiral ganglion proceeded simultanously in mice.

抄録全体を表示

There are many reports on the histopathology of presbycusis in humans and animals. But the differences in the pathologic changes of the inner ear occuring with aging among various laboratory animals have not been clarified. In order to study presbycusis in humans, it is necessary to find out the differences among various animals and compare these with the differences between humans and animals. In this study, hair cells of Wistar rats aged 4-32 months were observed using the surface preparation technique under a phase contrast microscope. At 4 and 7 months of age, the degeneration of hair cells was very slight. At 24 and 28 months, the loss of hair cells was greatest in the apical turn and also large in the basal end. Hair cell loss was most prominent in the third row of outer hair cells. Inner hair cell loss was small, but tended to increase at the apical turn.

抄録全体を表示

The trypsin-HCl method (Uehara) was applied to modiolar interstitial tissue to reveal adventitial aspect of modiolar vessels under SEM. The tunica media of spiral modiolar artery (SMA) was composed of thickly arranged spindle-like smooth muscle cells. Some of these cells had laminar folds on their surface which suggest contractility to some degree. Laminar folds and rich nerve fibers around the artery suggest that this artery plays an important role in cochlear blood flow volume control. Closely disposed ringed smooth muscle cells of primary branches of SMA were exchanged for branched type cells as the vessels ramify and/or become smaller. The pericyte of the capillary extended its elongated processes parallel, and occasionaly transverse, to the long axis. But the degree of branching of the processes was less in the modiolus than in the stria vascularis.

抄録全体を表示

It is supposed that the inner hair cells play an important role in hearing mechanisms, but the reports concerning the innervation patterns of the inner hair cells are less numerous compared with that of the outer hair cells. In this paper, a new technical approach is evaluated to study complicated patterns of the nerve endings on the inner hair cells.
The whole cochlea was embedded in the epoxy resin after being fixed by 3% glutaraldehyde and 1% OsO4 respectively. The embedded cochlea was bissected at the mid-modiolus and then dissected into each turn using a 0.15 mm thick diamond disc. These half-turns were re-embedded in a resin disc and observed in a light microscope. This disc was re-dissected out to be investigated by transmission electron microscopy. A high-voltage electron microscope (HVEM) was applied for quantitative evaluation of the nerve endings. The thick (590 nm) serial sections of the inner hair cells was examined with an accelerating voltage of 1000 kV in JEOL-1000.

抄録全体を表示

Longitudinal and horizontal sections were made in the stria vascularis of the guinea pig, and the fine structure of microtubules in the marginal cell was studied with the electron microscope. Many microtubules were found in the interdigitated portion of the marginal cell. In addition, the change of microtubules in the marginal cell of the stria vascularis after administration of cisplatin, sodium bromate and ethacrynic acid in guinea pigs. The distruction of mitochondrias and absence of microtubules were observed in the marginal cells after administration of cisplatin and sodium bromate, and the endolymphatic collapse was found in these. The edem of the stria vascularis was observed after administration of ethacrynic acid. In these marginal cells, many microtubules were remained.

抄録全体を表示